SSP markdown has incorrect label?

[degenaro]

Describe the bug

When using ssp generate with FedRAMP, a label 3_fr is incorrect, it should be just fr.

Add a test a case where SSP markdown for control 2.3 implements _fr statement with a control response. Verify in the assembly whether this appears or not.

To Reproduce

See PR https://github.com/oscal-compass/compliance-trestle/pull/1507

Markdown in question:

Expected behavior

• Correct markdown should be produced.
• Test case added to verify that an implemented control comprises the FedRAMP statement.

Screenshots / Logs.

N/A

Environment

Current version of trestle.